The present invention relates to medical technology but more particularly, to a device and method of determining the elasticity of the arterial wall.
I have been working on the oscillographic method of recording arterial pulses for many years now. When I started doing researches on haemodynamics, particularly pulse wave velocity, for which I was granted a Fellowship by the International Federation of University Women, I was confronted with the problem of recording arterial pulses which resembled the intra arterial pulses as closely as possible. This was essential as these said pulses showed the foot points or starting points of the recorded pulses which serve as reference points and which are marked for time interval measurements. After many repeated trials, I was able to design an attachment to the pickup microphone of the NEP pulse recording unit (Type A-643) of Sanborn. This attachment enabled me to record the desired pulses described above so that I was able to continue with my researches on pulse wave velocity. Said attachment is described in detail below.
In determining the elasticity of the arterial wall indirectly by measuring the time of the transmission of the pulse wave through the arteries, we use a xe2x80x9ccentral arteryxe2x80x9d and a xe2x80x9cperipheral arteryxe2x80x9d as reference points. The time interval between the instant the pulse is recorded in the xe2x80x9ccentral arteryxe2x80x9d and the instant that the same pulse is recorded in the xe2x80x9cperipheral arteryxe2x80x9d, is a measure of the time delay between the two reference points. In the medical literature, the left external carotid artery has always been used as the xe2x80x9ccentral arteryxe2x80x9d and the left femoral, brachial, radial or other arteries have been used as the xe2x80x9cperipheral arteryxe2x80x9d. The use of the left dorsalis pedis artery as a xe2x80x9cperipheral arteryxe2x80x9d has never been mentioned in the medical literature up to the present. It was my original idea to make use of the dorsalis pedis artery as the xe2x80x9cperipheral arteryxe2x80x9d on the assumption that I will be measuring a longer segment of the arterial system so that the margin of error for statistical analysis is less. Also, this artery is well exposed and easy to locate so that the sensor can be placed over it with ease.
Compared to other non invasive methods of measuring the pulse wave velocity (Doppler flow, ultrasounds and magnetic resonance) my device and method are simple, easy and fast to perform, reproducible, relatively inexpensive, compact and portable so that it is very suitable for epidemiologic studies in large populations especially in developing countries.
The primary object of this invention is to introduce a new device and an original method which has never been described in the medical literature for indirectly determining the elasticity of the arterial wall on a living subject.
The left external carotid artery as the xe2x80x9ccentral arteryxe2x80x9d has been described by many authors, but the use of the left dorsalis pedis artery as the xe2x80x9cperipheral arteryxe2x80x9d is my original idea and has not been mentioned in the medical literature up to the present. These arteries are well exposed, easily located and the distance between them is much longer compared to other methods heretofore described. The longer segment measured makes the margin or error for statistical analysis less, The subjects used for these studies are within a specific height range.
It is essential that the pulses recorded resemble as closely as possible the intra arterial pulse so that the foot points are clearly distinguishable as they are marked and used as reference points for time interval measurements. This has been achieved by using a special device that I have originally designed to be attached to the pick up microphone of the high frequency oscillograph. Specifically, the device is a circular metallic plate, one centimeter in diameter and one millimeter thick whose center is welded to the center of the pick up microphone with a solid tubular rod, one centimeter long and one millimeter in diameter. This device is placed on the skin over the artery. The anacrotic pulses recorded distinctly shows the foot points which serve as reference points in measuring the distances between the pulses of the left external carotid (xe2x80x9ccentral arteryxe2x80x9d) and left dorsalis pedis (xe2x80x9cperipheral arteryxe2x80x9d).